/**
 * This file is part of 1genia trampoline
 * Copyright (C) 2007 1genia (contact@1genia.com)
 *
 * This library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; version 3 of the License. 
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details. 
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; see the file COPYING.TXT.  If not,
 * write to the Free Software Foundation, Inc., 51 Franklin Street,
 * Fifth Floor, Boston, MA 02110-1301, USA. 
 **/
package com.genia.toolbox.persistence.memory.criteria.field;

import org.apache.commons.beanutils.PropertyUtils;

import com.genia.toolbox.persistence.basis.criteria.BasicCriteriaResult;
import com.genia.toolbox.persistence.exception.FieldDefinitionException;
import com.genia.toolbox.persistence.memory.criteria.MemoryCriteriaType;

/**
 * this class represent a property of a persistent object, or the object itself.
 */
public class MemoryPropertyField
    extends AbstractSimpleMemoryField
{

  /**
   * the <code>CriteriaType</code> of the object manipulated, or null if the
   * object is the main object of the query.
   */
  private final transient MemoryCriteriaType<?> type;

  /**
   * the property to extract, or null if the object is to be retrieved.
   */
  private final transient String property;



  /**
   * constructor.
   * 
   * @param type
   *          the <code>CriteriaType</code> of the object manipulated, or null
   *          if the object is the main object of the query
   * @param property
   *          the property to extract, or null if the object is to be retrieved
   */
  public MemoryPropertyField(final MemoryCriteriaType<?> type, final String property)
  {
    this.type = type;
    this.property = property;
  }



  /**
   * constructor.
   * 
   * @param property
   *          the property to extract, or null if the object is to be retrieved
   */
  public MemoryPropertyField(final String property)
  {
    this(null, property);
  }



  /**
   * constructor.
   * 
   * @param type
   *          the <code>CriteriaType</code> of the object manipulated, or null
   *          if the object is the main object of the query
   */
  public MemoryPropertyField(final MemoryCriteriaType<?> type)
  {
    this(type, null);
  }



  /**
   * Return the value of this field for the given line of result.
   * 
   * @param line
   *          the line of result we compute the field on
   * @return the value of this field for the given line of result
   * @throws FieldDefinitionException
   *           when there is an error in the definition of the field
   */
  @Override
  public Object getValue(final BasicCriteriaResult<?> line)
      throws FieldDefinitionException
  {
    final Object object = (type == null ? line.get() : line.get(type));
    if (property == null) {
      return object;
    }
    try {
      return PropertyUtils.getProperty(object, property);
    }
    catch (final Exception e) {
      throw new FieldDefinitionException(e);
    }
  }



  /**
   * returns if this <code>Field</code> is an aggregate.
   * 
   * @return <code>true</code> if this <code>Field</code> is an aggregate,
   *         <code>false</code> otherwise.
   */
  public boolean isAggregate()
  {
    return false;
  }

}
